In a broaching cutter for cutting internal teeth, a plurality of cutting blade stages each having a plurality of cutting blades arranged side by side in a circumferential direction are provided side by side in an axial direction. In the broaching cutter, a plurality of cutting blade stages for rough cutting and a plurality of cutting blade stages for finish cutting are sequentially provided side by side in a cutting direction. In the rough cutting, the cutting blades sequentially cut a processing hole in a workpiece in a radial direction to form intermediate shapes of the internal teeth. Then, in the finish cutting, the cutting blades sequentially cut the intermediate shapes of internal teeth in a circumferential direction to form the internal teeth.
For example, a broach for internal teeth gear processing described in Patent Document 1 uses four types of cutting blades for cutting a workpiece. Among the four types of cutting blades, a first cutting blade radially cuts the workpiece to form a tooth body portion in the workpiece, a second cutting blade cuts an inner peripheral portion at an inner periphery of the tooth body portion, a third cutting blade cuts an outer peripheral portion at an outer periphery (deep side) of the tooth body portion, and a fourth cutting blade cuts the tooth body portion in a circumferential direction so as to increase a circumferential width of the tooth body portion. In Patent Document 1, the first cutting blade is used for rough cutting of the tooth body portion.